1. Field of the Invention
This invention relates to electrically erasable and rewritable nonvolatile semiconductor memory devices, and semiconductor devices therewith.
2. Description of the Related Art
A low cost fuse memory device has been required, for making redundancy of an incorporated SRAM due to increasing its capacity, for tuning a driver such as an LCD driver individually after implementation, and for enhancing user-friendliness of personal identification information (an ID code, a decryption key, or IC card etc.).
A fuse having a poly-silicon or a wiring metal layer melted down by a laser or a current surge or a fuse having a gate insulator broken down by high voltage has been used as a fuse memory device formed in the standard logic CMOS process. However, these fuses having the meltdown portion or the breakdown portion cannot be applied to the foregoing usage because these are not reprogrammable.
An electrically erasable and rewritable fuse of a nonvolatile device having a floating gate can be manufactured in the logic CMOS process. However, additional mask steps over the standard logic CMOS process for manufacturing the floating gate does not worth the cost, and a floating gate device manufactured in a standard CMOS process deteriorates in data-retention due to a thinner insulator of a highly integrated circuit
U.S. Pat. No. 6,518,614 B1 and JPA2004-056095 show a nonvolatile memory device that is manufactured in the standard CMOS process, and JPA2005-353106 shows a nonvolatile memory device without the floating gate manufactured without the additional mask steps.